1. Field of the Invention
The present invention relates to an image capture and display control apparatus, an image capture and display control method, and an image capture and display system, for real time display on a display apparatus of images that have been captured by an image capturing apparatus.
2. Description of the Related Art
Image capture and display control apparatuses that are provided with an image capturing apparatus and a display apparatus, and that display captured images from the image capturing apparatus on the display apparatus in real time, are known (Japanese Patent Laid-Open No. S61-269582, Japanese Patent Laid-Open No. H5-35195, Japanese Patent Laid-Open No. 2004-325821). In apparatuses that perform the capture and display of images in real time, images are captured at a timing that is in accord with the frame rate of the image capturing apparatus, and images that are obtained are immediately displayed on the display apparatus.
In such real time capture and display of images, it is desirable for the time differential (hereinafter, the display delay time) between imaging by the image capturing apparatus and display of the image by the display apparatus to be short. However, in recent popular display devices, such as liquid crystal monitors, the timing of the display is controlled by the display apparatus, and problems with the image, such as tearing, occur when the image is output while ignoring the display timing of the display apparatus. Thus, even when imaging, for example, by the image capturing apparatus has finished and display of the image is possible, display of that image is delayed until the display timing of the display apparatus. Hereinafter, this waiting time will be referred to as the display waiting time.
The interval of the display timing of the display apparatus is determined by the display capabilities of the display apparatus. For example, consider the case of a liquid crystal monitor with a resolution of 1600×1200 pixels and a 60 Hz refresh rate. The display timing of the liquid crystal monitor is determined by the refresh rate, and in this case, the image information is displayed at an interval of approximately 16.7 ms. In other words, there is the possibility that as much as 16.7 ms will be wasted as the display waiting time between the point that display of the image by other than the liquid crystal monitor becomes possible and the actual display on the monitor.
As discussed above, image capturing apparatuses have an image capturing timing known as the frame rate, and display apparatuses have a timing at which display of an image occurs. Thus, since each apparatus has its own timing, there is the issue that unnecessary waiting for display occurs when capturing and displaying images in real time, and this causes the display delay time to become long. When the display delay time is long, the ability to track the display to the image that is being captured becomes worse. For example, in a case where a physician conducts surgery while performing fluoroscopy with an x-ray fluoroscopy apparatus for medical use, it is necessary for surgical operations by the physician to be reflected on the screen instantly, making it crucial for any delay in the display to be shortened as much as possible.
Particularly when the timing interval between the image capturing apparatus and the display apparatus is an integer multiple, it becomes necessary for a display waiting time to always be present during image capturing. FIG. 20 shows a simple example. For example, if the image capturing interval of the image capturing apparatus is 32 ms, and the display interval of the display apparatus is 16 ms, then it can be understood that the same display waiting time will occur for all images that are captured by the image capturing apparatus.